refactor mesh loading with textures in drakevisualizer.py
refactor mesh loading with textures in drakevisualizer.py

this supports texture information from vtm or vtp files,
previously only vtm files were supported.

openhumanoids/director,patmarion/director,openhumanoids/director,RobotLocomotion/director,manuelli/director,RobotLocomotion/director,mitdrc/director,RobotLocomotion/director,patmarion/director,mitdrc/director,manuelli/director,openhumanoids/director,mitdrc/director,patmarion/director,manuelli/director,patmarion/director,patmarion/director,RobotLocomotion/director,mitdrc/director,mitdrc/director,openhumanoids/director,manuelli/director,openhumanoids/director,manuelli/director,RobotLocomotion/director